Golden Alga in Texas

Impacts of Blooms

When a Golden Alga bloom occurs in Texas, the public wants to know how they will be affected. Although the Texas State Health Services Department has stated there are no dangers to human health from the toxins that produce these fish kills, there are effects on the environment and economy of the area.

Environmental Impacts

• Fishery - all species of fish can be affected and will die from toxins produced by golden alga, Prymnesium parvum. The numbers of fish killed depends on how much toxin is present, often influenced by how long the bloom remains active. Usually for a toxic bloom that only lasts one month or less, a partial fish kill occurs, and the waterbody recovers. The fish seem to seek shelter areas (ex. springs, seeps, or where creeks enter lakes). These fish try to stay where the golden alga toxins are diluted and/or are kept away from them. However, when a toxic bloom lasts many months and the fish kill involves a large part of the waterbody, then all populations of fish may be reduced. This means there are fewer fish to catch or reproduce. The forage fish grow quickly and have large numbers of eggs (such as sunfish, threadfin shad and most minnows). However, the game fish must have the forage fish for food and take many years to grow to maturity to reproduce. A waterbody with a major fish kill may need game fish stocking and can take years to recover. If there are subsequent fish kills caused by golden alga blooms, the recovery can take even longer. Clams are also killed by golden alga toxins, and their populations can be devastated by a bloom since they cannot move or escape like fish. Clam populations can be naturally reintroduced to the waterbody from upstream areas that were not impacted. This can take many years to occur.
• Wildlife -
  there do not appear to be impacts on terrestrial wildlife from Prymnesium parvum toxins. The toxins from the golden alga break down in acids (such as in the stomach). Researchers believe this is why no problems are seen when the wildlife drink from bloom water and eat the dead and dying fish. Surface exposure to the toxins (i.e. contact with the toxins via skin, fur, tongue, etc.) in wildlife do not have impacts because the same skin layers that protect organisms from drying out also protect them from the toxins. One potential problem is the lack of food source for wildlife after a large or prolonged fish kill; the fish the wildlife typically eat may be diminished and scarce. This can result in malnutrition that often leads to diseases in animals.
• Water quality - at this time, no major changes in the normal range of water quality parameters are seen in areas with golden alga blooms. These parameters are temperature, salinity, dissolved oxygen, pH, and conductivity. During the bloom the water can turn from green to a yellow color and have foaming when it is agitated. Shortly after the bloom is over, these conditions disappear. Often the water has more clarity (You can see deeper into the water during and after a bloom.) because there are fewer organisms such as other algae remaining in the water.

Economic Impacts

The greatest economic impact is to communities or businesses that depend on visitors to an affected waterbody. During the fish kill, people may avoid the lake due to the dead fish. The fishing may is not be as good as before in certain areas, and anglers may go to other lakes. Even after the algal bloom is over, people may still avoid the lake. Many people come from out of state to enjoy the Texas lakes. This avoidance can cause a loss in revenue for fishing guides, vacation camp operators, parks, hotels, motels, restaurants, clothing stores, gas stations, and more. If the revenue to these businesses is down, the businesses may spend less money and be able to hire fewer people. This can affect the local, city, and county economy. Reduced sales taxes collected by these businesses may impact the state’s economy. This can affect the entire state.

Estimating the Economic Impacts of Golden Algae (Prymnesium parvum) on Recreational Fishing at Possum Kingdom Lake (PDF 328 KB)

top of page